In vertical power semiconductor devices a load current flows between a first surface at a front side and a second surface on the back of a semiconductor die. Since the dielectric breakdown field strength in silicon carbide is significantly higher than in silicon, silicon carbide semiconductor devices can be significantly thinner than equivalent silicon devices for the same blocking voltage. Therefore silicon carbide semiconductor devices can combine high breakdown voltages of more than 600 V with significantly lower on-state resistance than their silicon counter parts. Due to the comparatively thin drift zone, the comparatively low charge carrier mobility in the channel region dominates the on-state resistance of vertical silicon carbide devices at least for voltage classes with blocking voltages up to 1200 V.
There is a need for vertical semiconductor devices which combine materials with high dielectric breakdown field strength with low RDSon.